1. Field of the Invention
The present invention relates to an image forming apparatus including an electrophotographic system.
2. Description of the Related Art
In recent years, an electrophotographic image forming apparatus which forms an image by forming an electrostatic latent image as a result of charging and exposing a surface of a photoreceptor drum, affixing the charged toner to the electrostatic latent image so as to form a toner image, and transferring the toner image to recording paper is being broadly used. With this kind of image forming apparatus, upon transferring the toner image to the recording paper, the recorded paper that is sandwiched between the photoreceptor drum and a transfer roller is charged by the transfer roller. The toner is thereby transferred to the recording paper by electrostatic force. Moreover, since it becomes easy for the recording paper to stick in the photoreceptor drum by the electrostatic force, the image forming apparatus described in following Japanese Patent Application Laid-open No. 2002-365923 adopts a configuration of eliminating static from the recording paper with a static elimination needle to which a static elimination bias was applied.
Meanwhile, when the recording paper passes through a transfer nip portion between the photoreceptor drum and the transfer roller and the portion of the recording paper that passed through the transfer nip portion is separated from the photoreceptor drum, the posture of the portion of the recording paper becomes unstable. The portion of the recording paper where the posture is unstable tends to be drawn toward the static elimination needle to which a static elimination bias was applied. When a portion of the recording paper comes too close to the static elimination needle, a closed circuit connecting the transfer roller, the recording paper and the static elimination needle is formed, and the electric charge that was supplied to the recording paper via the transfer roller will escape through the static elimination needle. In the foregoing case, since the recording paper will not be sufficiently charged, toner will not be sufficiently affixed to the surface of the recording paper, and there is a possibility that transfer defects such as white spots will occur.